(1) Field of the Invention
The present invention relates to an arrangement of an internal-combustion engine, and in particular relates to an ignition mounting arrangement in an internal-combustion engine.
(2) Description of the Prior Art
Conventionally, magneto ignition systems have been mainly employed as the ignition systems of internal-combustion engines having no battery or other external power supply, such as multi-purpose engines and small outboard motors.
Examples of magneto ignition systems include transistor magneto ignition system and CDI ignition system.
As shown in FIGS. 1 and 2, in a transistor magneto ignition system, a magnet 112d is disposed at the periphery of a flywheel 112 of an engine 100 while a core 125 of an igniter 124 is positioned over engine case 113 via spacer 114 so as to oppose the magnet 112d, where by a high voltage generated by the igniter 124 is applied to a spark plug 22 to achieve ignition. This method has the advantage of reducing the product cost because igniter 124 is low in cost, hence has been widely used for multi-purpose engines which are used at a fixed engine speed.
On the other hand, in a CDI ignition system, as shown in FIGS. 3 and 4, a magnet 222d is disposed on the inner side of a flywheel 222 of an engine 200 so as to cause an exciter coil 201 to charge a capacitor (not shown) in a CDI unit 202, whereby a high voltage is applied to a spark plug 22 by an igniter 224 disposed near a cylinder head 21 to achieve ignition. This method has the advantage of being easy in performing various controls because ignition timing can be set freely, hence has been used for engines which need relatively high-performance control. A reference numeral 203 in the drawings designates a pickup coil which detects the engine speed.
However, these conventional ignition systems have the following drawbacks. That is, the transistor magneto ignition system suffers an inconvenience that there are cases when the engine speed is low where it is impossible to obtain a high enough generation voltage compared to the required voltage, failing to provide the spark because variation in magnetic flux is too small and also there is an inconvenience of the setting of ignition timing being less flexible.
For the CDI ignition system, since exciter coil 201, pickup coil 203, CDI unit 202 and igniter 224 are all provided separately, this system needs more parts compared to the transistor magneto system, resulting in an increased cost.
In this way, the feature of the ignition system determines the characteristic of a conventional magneto ignition engine, either of a cost-oriented type or of a high-performance type. Therefore, it has been difficult to provide development of a series of various models based on one engine base to meet the demands of various users.
The present invention has been devised in view of the above conventional problems, it is therefore an object of the present invention to provide an ignition mounting arrangement in an internal-combustion engine in which either an inexpensive transistor magneto ignition system or high-performance CDI ignition system can be mounted interchangeably so as to provide a series of various models of engines such as outboard motors based on one type of engine, whereby price difference of the engines due to performance difference can be suppressed.
In order to achieve the above object, the present invention is configured as follows:
In accordance with the first aspect of the present invention, an ignition mounting arrangement in an internal-combustion engine, includes: a flywheel with a magnet, disposed at one end of the crankshaft; and an ignition coil unit having a generator coil, arranged close to the flywheel, wherein the voltage generated by the generator coil as the flywheel turns is controlled by the ignition coil unit so as to output a high voltage to a sparkplug, and is characterized in that it is possible to mount as the ignition coil unit either a CDI ignition coil unit which is integrally configured of a generator coil, an ignition timing detecting means for detecting the ignition timing based on the rotation of the flywheel and an ignition controller for controlling the ignition timing, or a transistor magneto ignition coil unit having approximately the same shape as that of the CDI ignition coil unit, and the flywheel to be mounted can be selected in accordance with the ignition type of the ignition coil unit to be mounted.
In accordance with the second aspect of the present invention, the ignition mounting arrangement in an internal-combustion engine having the above first feature is characterized in that the ignition coil unit comprises an igniter and core portions of a generator coil elements so that the core portions of the generator coil elements are arranged close to the igniter on both side thereof, sandwiching the igniter when viewed from the top, and the core portions of the generator coil elements are positioned outside the flywheel and projected closer to the magnet of the flywheel than the igniter is at the positions where they oppose the magnet.
In accordance with the third aspect of the present invention, the ignition mounting arrangement in an internal-combustion engine having the above first feature is characterized in that the engine is used as an outboard motor with the crankshaft arranged approximately vertically and the cylinder portion directed to the rear,
the flywheel is fixed at one end of the crankshaft which is projected outside over the upper side of the engine case so that it can rotate as the crankshaft turns;
the ignition coil unit is attached to an attachment boss projected at the top on the upper side of the engine case and is arranged on the cylinder head side along the periphery of the flywheel; and
an ignition cord is provided to connect the spark plug located at the cylinder head to the ignition coil unit.
In accordance with the fourth aspect of the present invention, the ignition mounting arrangement in an internal-combustion engine having the above second feature is characterized in that the engine is used as an outboard motor with the crankshaft arranged approximately vertically and the cylinder portion directed to the rear,
the flywheel is fixed at one end of the crankshaft which is projected outside over the upper side of the engine case so that it can rotate as the crankshaft turns;
the ignition coil unit is attached to an attachment boss projected at the top on the upper side of the engine case and is arranged on the cylinder head side along the periphery of the flywheel; and
an ignition cord is provided to connect the spark plug located at the cylinder head to the ignition coil unit.
In the ignition in an internal-combustion engine according to the present invention, a CDI ignition coil unit for a CDI ignition system which is integrally formed of a generator coil, an ignition timing detecting means for detecting the ignition timing based on the rotation of the flywheel and an ignition controller for controlling the ignition timing or a transistor magneto ignition coil unit which is designed to be approximately the same configuration as that of the CDI ignition coil unit, may be used as the ignition coil unit. That is, either ignition coil unit can be mounted. Further, the flywheel to be mounted can be selected in accordance with the ignition type of the ignition coil unit to be mounted. Therefore, the inexpensive transistor magneto ignition system and the high-performance CDI ignition system can be mounted interchangeably on a single engine base. Thus, it is possible to provide multiple models of engines using the same type of engine base, at a sharply reduced manufacturing cost compared to the case where multiple types of engines are manufactured.
The ignition coil unit is configured so that the core portions of the generator coil elements are arranged close to an igniter on both side thereof, sandwiching the igniter when viewed from the top. Further, the core portions of the generator coil elements are positioned outside the flywheel and close to the magnet located on the flywheel at the positions where they oppose the magnet. When the transistor magneto ignition system or CDI ignition system is adopted as the ignition coil unit, either ignition coil unit can be mounted simply by changing the igniter configuration and the positional relationship of the igniter relative to the core portions of the generator coil elements, without significantly changing the mounted positions of the core portions of the generator coil elements and without changing the layout of the other components.
Moreover, in the engine of an outboard motor with the crankshaft arranged approximately vertically and the cylinder portion directed to the rear, the flywheel is fixed at one end of the crankshaft which is projected outside over the upper side of the engine case so that it can rotate as the crankshaft turns while the ignition coil unit is arranged on the cylinder head side along the periphery of the flywheel. Therefore, it is possible to arrange the ignition coil unit at a position close to the spark plug and still within the silhouette of the engine from the top, realizing a space-saving layout. Further, since the ignition coil unit is attached to an attachment boss projected at the top on the upper side of the engine case, it is possible to attach it with simple components.